Efforts to treat industrial waste water are well known. One of the more successful of the techniques for treating industrial waste water is disclosed in U.S. Pat. No. 4,069,148 to Hutton et al., in which industrial waste water is treated by a biological treatment process in the presence of activated carbon or fuller's earth, the biological treatment being enhanced by the presence of the activated carbon or fuller's earth to produce a relatively pure water product which, for the most part, can be directly disposed of into natural bodies of water.
In the apparatus for carrying out the patented process, there is provided means for providing a primary treatment, which includes a piece of equipment, commonly called a neutralizer, for adjusting the acidity of the waste water, and a piece of equipment called a clarifier into which the waste water which has had the acidity adjusted is directed in order to permit solids to settle out from the waste water. Moreover, in practical use, the apparatus for carrying out the patent process also includes such pieces of equipment as flow splitters, which split the flow of industrial waste water into several streams for treatment in parallel parts of the overall apparatus, and also additional treatment apparatus in which flocculating agents and nutrients for supporting the biological action in the biological treatment zone are added. There are also further clarifiers in which the liquid is again allowed to stand so that further solids can separate out.
In each of these pieces of equipment, the surface of the liquid is exposed to the atmosphere, and the malodorous volatile organic gases which are present in the waste water begin to escape into the atmosphere. This process is often promoted by the agitation of the waste water in these pieces of equipment.
The prior art process described above is therefore not concerned with the treatment of these volatile organic gases and accordingly these malodorous gases are permitted to escape into the atmosphere resulting in pollution of the surrounding atmosphere.
Recently, the Environmental Protection Authorities of the various state governments have become increasingly strict on the quality of gases which are allowed to escape from industrial operations, and it is now becoming necessary to consider these gases and how to treat them so as to remove substantially all of the pollutants therefrom.
It is, of course, known to treat gases including volatile organic gases therein for removal of such volatile organic gases. One common way of doing this is to pass the gases over activated carbon particles, or the like, which adsorb the gases selectively, allowing the harmless gases, such as oxygen or carbon dioxide, to pass therethrough.
Another type of treatment which has been proposed is to pass the gases containing the volatile organic gases through naturally decomposable organic material, such as ground-up plants, tree limbs, or the like, for converting such material to mulch, during which the volatile organic gases are partially adsorbed from the stream of gases being passed through the mulch.
Neither of these types of gas purification processes has been found to be particularly effective. Difficulties occur in the use of the activated carbon particles, since contact with air results in an oxidation process which is exothermic, causing elevation of the temperature of the carbon particles, and tending to cause fires in the treatment apparatus. The quantity of natural organic material needed for removal of the volatile organic gases from a stream of flowing gases is so large that if the stream of flowing gases is at all voluminous, an impractically large amount of natural organic material is needed for the purification process.